About these ads

Climate: Is the Southwest ‘stuck’ in a drought pattern?

s

s

NOAA’s winter outlook offers little relief for Arizona, New Mexico

By Bob Berwyn

FRISCO — Drought conditions may persist across the southwestern U.S. this winter and may redevelop across the Southeast, according to the seasonal outlook from NOAA’s Climate Prediction Center.

“Even though we don’t have La Niña, the atmosphere across the Pacific seems to be stuck in a La Niña mode … It’s been quite surprising to us, how persistent the pattern is,” said Mike Halpert, acting director of the Climate Prediction Center.

Parts of the Southwest, especially New Mexico, have been experiencing one of the driest periods on record, and Halpert said there is “decent agreement” in the CPC’s models on the climate signal that has resulted in the persistent trend. Continue reading

About these ads

Climate study shows that deforestation of the Amazon could dry out the western United States

Shifts in precipitation patterns would have big consequences for agriculture, forests and municipal water supplies

kj

Research suggests that deforestation will likely produce a weather cycle over the Amazon consisting of abnormally dry air in the sun-scorched northern Amazon around the equator weighted by wetter air in the cooler south (left). The Princeton-led researchers found that the Amazon pattern would be subject to meandering high-altitude winds known as Rossby waves that move east or west across the planet (center). The Rossby waves would move the dry end of the Amazon pattern directly over the western United States from December to February, while the pattern’s rainy portion would be over the Pacific Ocean south of Mexico (right). Image courtesy Princeton University.

By Summit Voice

FRISCO — Continued deforestation in the Amazon region could have significant impacts on the weather in North America, according to Princeton researchers, who used fine-grained climate models to simulate how precipitation patterns could shift in the future.

Their findings suggest that  total deforestation of the Amazon may significantly reduce rain and snowfall in the western United States — specifically, 20 percent less rain for the coastal Northwest and a 50 percent reduction in the Sierra Nevada snowpack, a crucial source of water for cities and farms in California.

“The big point is that Amazon deforestation will not only affect the Amazon — it will not be contained. It will hit the atmosphere and the atmosphere will carry those responses,” said lead author David Medvigy, an assistant professor of geosciences at Princeton. Continue reading

Climate: El Niño unusually active in 20th century

New study may help show how El Niño will respond to global warming

ghj

Tracking El Niño …

By Summit Voice

FRISCO — Powerful El Niño events during recent decades are outside the norm of the last 600 years, climate researchers said this week, after finding that the cycles of warmer-than-average sea surface temps in the equatorial Pacific appear linked to global temperatures.

“Our new estimates of El Niño Southern Oscillation (ENSO) activity of the past 600 years appear to roughly track global mean temperature,” said Shayne McGregor, of the University of New South Wales. “But we still don’t know why.”

The team of climate scientists, including researcher with the University of Hawaii International Pacific Research Center and the NOAA Geophysical Fluid Dynamics Laboratory, said their findings (published in Climate of the Past) help resolve some of the uncertainties surrounding historic ENSO cycles, which can trigger flooding and droughts across different parts of the world. Continue reading

How will global warming affect El Niño?

Study shows how external influences shape Pacific weather patterns

ghj

New research may help show how global warming will affect El Niño.

By Summit Voice

FRISCO — By studying coral samples from a remote Pacific atoll, Australian researchers say they’ve found evidence that external influences can change the intensity of the periodic El Niño cycle. By extension, they said, human-caused global warming could also alter the pattern, though the observational record is too short to determine whether that’s already happening.

The research was led by scientist with the ARC Centre of Excellence for Climate System Science and  published in Nature Geoscience.

“Our research has showed that, while the development of La Niña and El Niño events is chaotic and hard to predict, the strength of these events can change over long time spans due to changes in the global climate,” said one of the paper’s authors, Australian climate researcher Dr. Steven Phipps. Continue reading

Summit Voice: Week in review

Climate, cannabis and apex predators …

anomnight-current-small

Whither the weather?

By Summit Voice

FRISCO — One of the top news stories in Colorado last week was the dramatic change in the federal government’s position on legal use of marijuana in Colorado. After decades of intolerance, U.S. Attorney General Eric Holder indicated that the feds won’t seek to challenge Colorado’s new pot regime — at least for now. That leaves the state free to administer recreational sales of cannabis, as long as there is a robust state-based regulatory structure. Read the Summit Voice story, which includes the full text of the new guidance from the feds: Feds ease stance on marijuana.

In a couple of email interviews, Summit Voice explored the seasonal weather outlook. Making forecasts three months in advance is dicey at best, an in the absence of a clear El Niño or La Niña signal, meteorologists are struggling even more than usual to pin down upcoming patterns: Climate: With no Niño — what’s a forecaster to do?

For Mexican gray wolves living in the southwestern United States, the news was good. Rather than fighting conservation groups, the U.S. Fish and Wildlife Service backed down in the face of several lawsuits to give the predators a little more room to roam in the deserts of Arizona and New Mexico: Mexican gray wolves will get more room to roam.

A forest study in the eastern U.S. has implications for forest management here in the West, as well, showing that, when it comes to biodiversity, forest species need a mix of towering old growth and cleared areas, which are seen as important for birds just before they migrate: Study: Forest clearings crucial for some birds. Continue reading

Climate: With no Niño — what’s a forecaster to do?

Fall and winter outlook still murky

j

Seasonal weather forecasters look out to sea surface temperatures in the equatorial Pacific to get an idea of what weather patterns may bring.

asdf

Without a stron El Niño or La Niña in the outlook, forecasters are not confident of projecting pronounced temperature or precipitation anomalies.

By Bob Berwyn

FRISCO — With no strong El Niño or La Niña on the horizon, forecasters are struggling even more than usual to develop seasonal outlooks for the western U.S. The periodic El Niño-La Niña cycle is a large-scale shift in the Pacific involving a complex interplay of winds, ocean currents and sea surface temperatures.

In the U.S. the warm El Niño phase is associated with wetter than average conditions in the Desert Southwest and California, and can result in below average precipitation in the Pacific Northwest.

La Niña, on the other hand, has been linked with Southwestern drought conditions and heavy precipitation in the Pacific Northwest. That persistent moist flow off the northwestern Pacific can also favor parts of Colorado with good winter snows, but the ENSO climate signal is more marginal in Colorado than in other areas. Continue reading

Climate: Better El Niño forecasting ahead?

Early warning could help regional preparedness efforts

A new climate model could help project El Niño conditions a year in advance.

A new climate model could help project El Niño conditions a year in advance.

By Summit Voice

FRISCO — Forecasting the emergence of El Niño well in advance has long been a goal of climate scientists and a team of German researchers say they may have devised a model that extends the lead time to a year.

Published recently in the Proceedings of the National Academy of Sciences, their paper describes how the model uses high-quality data of air temperatures as the basis for making long-term projections about El Niño, a warm phase of a periodic Pacific Ocean cycle that affects climate and weather around the world.

“Enhancing the preparedness of people in the affected regions by providing more early-warning time is key to avoiding some of the worst effects of El Niño,” said Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research, who co-authored the paper with Josef Ludescher, of Justus-Liebig Universität Giessen. Continue reading

Follow

Get every new post delivered to your Inbox.

Join 7,491 other followers